gwen: as a week of special pbs coverage of gun violence draws to a close, we examine the ongoing debate in washington, in state houses in city halls. >> if a gun that was used 69 days ago to slaughter 20 children and six adults isn't an assault weapon, then they don't exist. >> a debate that is just beginning. covering the week, john harwood of cnbc and the "new york times." david sanger of the "new york times." molly ball of the atlantic, and sari horwitz of "the washington post." >> award-winning coverage and adge sys, covering history as it happens. live from our nation's capital, this is "washington week" with gwen ifill. corporate funding for washington week is provided by -- >> we know why we're here, to chart a greener path in the air and in our factories. >> to find cleaner more efficient ways to power flight. >> and harness our technology for new energy solutions. >> around the globe the people of boeing are working together to build a better tomorrow. >> that's why we're here. >> additional corporate funding for "washington week" is provided by prudential. additional funding i